1. Field of the Invention
The present invention pertains to a device for damping vibrations and reducing noise. The invention more particularly concerns the reduction or elimination of vibrations and rubbing of a flat ribbon cable contained within an automotive clockspring so as to reduce noise levels.
2. Discussion of the Background
Devices are well known in the art for damping the sound emanating from automobile clocksprings due to the vibration and rubbing noises of the flat ribbon cable contained within the clockspring housing. An automotive clockspring is an electrical connector or rotary transducer which electrically connects a rotatable airbag assembly mounted on the steering wheel to stationary crash sensors located elsewhere on the vehicle. An automotive clockspring typically includes a housing and a cover mounted to the housing so as to form a cavity therebetween. Rotatably mounted within the cavity is a hub. The clockspring housing is non-rotatably mounted to the steering column, while the hub is attached to the rotatable airbag assembly. A flat ribbon cable is wound around the hub. One end of the flat ribbon cable terminates at the stationary housing or cover and the other end terminates at the hub. The end of the flat ribbon cable terminated at the hub is then connected to an electrical cable which connects to the airbag assembly. During use, the flat ribbon cable is either spooled or un-spooled around the hub when the steering wheel is turned in one direction or the other direction.
One solution to solving the problem includes placing a carrier member within the cavity of the clockspring between the hub and the housing. Typically, the carrier member includes roller members. The carrier member is used to fill-up the empty space of the cavity and to compress a portion of the flat ribbon cable toward the inner most radius of the cavity and to press another portion of the flat ribbon cable toward the outermost radius of the cavity. Such a distribution of the flat ribbon cable requires the use of a turned back portion of the flat ribbon cable as is exemplified in U.S. Pat. No. 5,865,634, which is hereby incorporated herein by reference. The clockspring disclosed in U.S. Pat. No, 5,865,634 uses a carrier member having roller members, which allows such a device to use a short length of flat ribbon cable. Using a short length of flat ribbon cable is important since flat ribbon cable is expensive. The drawback of a clockspring having a carrier member is the increased cost of manufacturing and inventorying the piece parts of such a clockspring. A further, inherent drawback of such a design is the increased weight of the clockspring.
Another solution to the problem includes placing vibration dampers within the cavity of clockspring as is disclosed in U.S. Pat. No. 5,490,793, which is hereby incorporated herein by reference. The design and placement of the vibration dampers does not allow for use of the uniform distribution and placement of the flat ribbon cable as is possible with the design disclosed in U.S. Pat. No. 5,865,634. Thus, a minimal length of flat ribbon cable is not used in the vibration damper design. However, the vibration damper design includes fewer parts than the carrier member design, and, hence, the vibration damper design weighs less than the carrier member design.
Thus, there is a need for a low-cost, reliable, light-weight, and simple to manufacture clockspring which does not generate audible sounds due to vibration and relative rubbing of the coils of the flat ribbon cable.